Brake Caliper Rebuild - Rear

This procedure covers disassembly, cleaning, inspection, and rebuild of the rear brake calipers on a 2015-2020 Ford F-150 3.5L EcoBoost, including piston removal, seal replacement, and proper lubrication.

Warnings

Tools required

Parts

• Rear brake caliper rebuild kit (includes pistons, seals, boots) × 2 — Use OEM Ford specification or quality aftermarket equivalent
• Brake caliper slide pin boot kit (if damaged) × 2 — Often included in rebuild kit
• Copper crush washers for brake line (if disconnecting) × 4 — Use OEM specification

Fluids

• Motorcraft DOT 4 LV Brake Fluid — 1 qt

Preparation

1. Park vehicle on level ground, place transmission in Park, and engage parking brake firmly
2. Loosen rear wheel lug nuts 1/4 turn while vehicle is still on ground
3. Raise rear of vehicle using floor jack at manufacturer-specified jacking points and support on jack stands rated for vehicle weight
4. Remove rear wheels completely and set aside
5. Verify vehicle is stable on jack stands before working underneath
6. Place drain pan under work area to catch brake fluid
7. Pump brake pedal several times, then open hood and remove approximately half the brake fluid from master cylinder reservoir using turkey baster or fluid transfer pump to prevent overflow during caliper compression
8. Have clean workspace prepared with all rebuild kit components laid out for inspection

Procedure

1. 1

   Remove caliper from mounting bracket
   Using appropriate socket, remove the two caliper slide pin bolts that secure the caliper to the bracket. Support the caliper weight and carefully lift it off the brake pads and rotor. Do NOT let the caliper hang by the brake hose - support it with a wire hanger or bungee cord attached to the suspension. If you need complete access for rebuild, attach a bleeder hose to the bleeder screw, place other end in catch container, open bleeder screw, and carefully disconnect the brake line from the caliper. Immediately cap or plug the brake line to prevent fluid loss and contamination.
   Torque spec

   Caliper Slide Pin Bolts35 Nm (26 lb-ft)

   Bleeder Screw10 Nm (7 lb-ft)
2. 2

   Remove brake pads and hardware from bracket
   If not already removed, slide the brake pads out of the caliper bracket. Remove any anti-rattle clips, shims, or hardware. Inspect the bracket slide surfaces for scoring or damage. Clean the bracket thoroughly with brake cleaner and wire brush, paying special attention to the pad slide areas.
3. 3

   Disassemble caliper and remove piston
   Move to a clean workspace with the caliper positioned over a workbench with clean rags underneath. Remove the dust boot from the piston by carefully prying it out of the caliper bore groove. To remove the piston: If brake line is still connected, have an assistant gently press the brake pedal while you control the piston emergence (STOP before piston comes completely out). If brake line is disconnected, use controlled compressed air applied to the brake fluid inlet port - place a block of wood or thick folded rag between the piston and caliper body to catch it as it emerges. Apply air in SHORT bursts and keep fingers clear. Once piston is partially out, carefully wiggle and pull it free by hand.
   ⚠️The piston can eject violently under air pressure. Always use a block of wood or thick cloth to restrain it. Never place fingers in line with the piston path.
4. 4

   Remove internal piston seal
   Inspect the piston bore carefully. You will see a square-section rubber seal seated in a groove inside the caliper bore. Using a small plastic pick or wooden tool (NEVER metal tools that can scratch the bore), carefully pry out the piston seal from its groove. Take care not to scratch or gouge the caliper bore surface - any scoring will cause leaks and require caliper replacement.
   ⚠Do not use metal tools to remove the seal. Even minor scratches in the caliper bore will cause fluid leaks and seal failure.
5. 5

   Clean and inspect all components
   Thoroughly clean the caliper bore, piston, and all caliper passages with brake cleaner and lint-free rags. Inspect the caliper bore for any pitting, scoring, rust, or corrosion - if present, the caliper must be replaced, not rebuilt. Inspect the piston chrome plating for chips, peeling, or corrosion - if damaged, use the new piston from the rebuild kit. Clean the exterior caliper body and all bolt holes. Blow out all passages with compressed air. Everything must be absolutely clean before reassembly.
   ℹ️Even minor bore damage will cause the rebuild to fail. Be honest in your inspection - a $30 rebuild kit is wasted if the caliper bore is compromised.
6. 6

   Install new piston seal
   Remove the new piston seal from the rebuild kit. Lubricate it lightly with clean brake fluid (DOT 4 LV only - never petroleum products). Carefully work the seal into the groove inside the caliper bore using only your fingers. Ensure the seal is seated evenly all the way around the groove with no twists or folds. The seal should sit flat in its groove.
   ⚠Use only fresh DOT 4 LV brake fluid or the specific lubricant provided in the rebuild kit. Petroleum-based products will destroy rubber seals instantly.
7. 7

   Install piston and dust boot
   Lubricate the new or cleaned piston with clean brake fluid. Carefully insert the piston into the caliper bore, ensuring it enters straight and does not cock to one side. Use steady, even pressure to push the piston into the bore - it should slide in with moderate resistance. Push the piston nearly flush with the caliper body or until it seats against the seal. Install the new dust boot by stretching it over the piston and seating the outer edge into the caliper body groove. Ensure the boot is fully seated with no folds or gaps.
   ⚠The piston must enter the bore perfectly straight. Forcing a cocked piston will damage the new seal and ruin the rebuild.
8. 8

   Service caliper slide pins
   Remove the caliper slide pins from the bracket by pulling them out. Clean the pins thoroughly with brake cleaner and inspect for corrosion, scoring, or damage - replace if worn. Clean out the pin bores in the bracket. If the pin boots are torn or deteriorated, replace them with new boots from the kit. Apply a thin coating of high-temperature silicone brake grease to the slide pins (never use petroleum-based grease). Reinstall the pins and boots into the bracket, ensuring boots are fully seated.
   ⚠Seized or improperly lubricated slide pins cause uneven pad wear and reduced braking performance. This step is critical for proper brake function.
9. 9

   Reinstall caliper assembly
   If brake line was disconnected, install new copper crush washers and reconnect the brake line to the caliper, tightening to manufacturer specifications. Position the brake pads and hardware into the caliper bracket. Carefully position the rebuilt caliper over the pads and bracket. Install the caliper slide pin bolts and hand-tighten. Apply silicone brake grease to the slide pin bolt threads and contact surfaces as specified. Torque the caliper slide pin bolts to specification using a calibrated torque wrench.
   Torque spec

   Caliper Slide Pin Bolts35 Nm (26 lb-ft)
10. 10

    Repeat process for opposite side
    Perform steps 1 through 9 for the opposite rear caliper. Both rear calipers should be rebuilt together to ensure even braking performance and prevent brake pull.
    ℹ️Always rebuild or replace brake components in axle sets (both sides). Mismatched calipers can cause dangerous brake pull or uneven wear.
11. 11

    Bleed brake system
    Fill the master cylinder reservoir to the MAX line with fresh Motorcraft DOT 4 LV brake fluid. Starting with the brake caliper farthest from the master cylinder (typically passenger rear), attach clear tubing to the bleeder screw and place the other end in a clean container with a small amount of brake fluid. Have an assistant pump the brake pedal 3-4 times and hold pressure. Open the bleeder screw 1/2 turn while assistant maintains pedal pressure - fluid and air will flow into the container. Close the bleeder screw before the pedal reaches the floor. Repeat until no air bubbles appear in the tubing. Tighten bleeder screw to specification. Repeat for driver rear, passenger front, and driver front in that order. Check and refill master cylinder frequently during bleeding - never let it run dry.
    ⚠️If the master cylinder runs dry during bleeding, air will enter the ABS system requiring professional scan tool bleeding. Monitor fluid level constantly.
    Torque spec

    Bleeder Screw10 Nm (7 lb-ft)
12. 12

    Reinstall wheels and perform initial checks
    Reinstall the rear wheels onto the hubs. Install lug nuts and hand-tighten in a star pattern. Lower the vehicle until wheels just touch the ground but weight is still on jack stands. Using a calibrated torque wrench, torque the wheel lug nuts to specification in a star pattern. Fully lower the vehicle and remove jack stands. With vehicle still in Park, pump the brake pedal multiple times until it becomes firm and holds pressure. Check master cylinder fluid level and top off to MAX line if needed.
    ⚠️The brake pedal MUST feel firm before moving the vehicle. A soft or spongy pedal indicates air in the system or improper assembly. Do not drive until this is corrected.
    Torque spec

    Wheel Lug Nuts140 Nm (103 lb-ft)

Reassembly

1. Ensure all bleeder screws are tightened to proper torque specification
2. Verify master cylinder is filled to MAX line with fresh DOT 4 LV brake fluid and cap is secure
3. Check all brake line connections for leaks - wipe clean and inspect after pedal pumping
4. Verify caliper slide pin bolts are torqued to specification with proper brake grease applied
5. Confirm wheel lug nuts are torqued in proper star pattern to specification
6. Visually inspect the entire brake system for any loose components, leaks, or missing hardware

Verification

• With engine off, pump brake pedal firmly 10-15 times - pedal should become firm and maintain height. A sinking pedal indicates air in the system or leaks
• Start engine and verify brake pedal remains firm with power assist engaged. Pedal should not sink under sustained pressure
• Check for brake fluid leaks at all caliper connections, bleeder screws, and brake lines
• In a safe, traffic-free area, perform multiple moderate brake applications from 15-20 mph to verify proper braking function and bed in the rebuilt calipers
• Test for brake pull - vehicle should stop straight without pulling to either side
• Perform a firm stop from 30 mph in a safe area - brakes should engage smoothly and evenly with no noise, vibration, or pulling
• After test drive, recheck all caliper bolts for proper torque and inspect for any fluid leaks
• Check brake fluid level in master cylinder after test drive and top off if needed
• Plan for a 200-mile break-in period with moderate braking - avoid hard stops to allow proper seating of rebuilt components

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